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Registering as self-employed in Spain isn't complicated, but there is an order to it that you need to follow. Start working without completing both registrations done correctly - or miss the deadline - and you could lose your right to the reduced flat-rate contribution, rack up backdated payments, and face surcharges. That's a stressful start to what should be an exciting chapter.
With Monzo Business, you can register as an autónomo when you apply for your Monzo Business Account, so you can tick off business setup and business bank account in one go.
If you want to do it yourself, you need to complete two mandatory steps: registering with Hacienda and social security. We'll walk you through both of them here.
What you need before you start: your Cl@ve or digital certificate
Before you can do anything online with the Spanish government, you need a way to identify yourself digitally. Without one of these, you won't be able to complete either registration.
You've got two options:
Cl@ve - the government's identification app, which lets you verify your identity using your Spanish ID (DNI) or foreigner's ID (NIE) without needing a digital certificate. You can set it up at clave.gob.es. It's quicker to get and works for both hacienda and social security registration. If you don't have either yet, start here.
Digital certificate - You can get a digital certificate from Spain's National Mint (Fábrica Nacional de Moneda y Timbre FNMT). You'll need to apply online at sede.fnmt.gob.es and verify your identity using one of the verification methods available to you, which can include in-person or remote identification. Once verified, you can download your certificate and use it for online government services.
Step 1: Register with Hacienda: modelo 036
Your first step is to register your economic activity with Hacienda (Agencia Tributaria) using modelo 036.*
Modelo 036 is the form used to register your economic activity with Hacienda. It covers all autónomos, whether they’re Spanish resident, deal in intra-EU transactions, or have employees.
What modelo 036 does:
Registers you for IRPF (income tax) and IVA (VAT)
Records the economic activity or activities you're carrying out and the relevant IAE classification (we’ll talk more about this in the next section)
Allows you to declare which tax regime you want your income tax to be calculated using (the options to pick between are direct estimation, simplified direct estimation or módulos)
IAE epígrafe and CNAE Code- what’s the difference?
When registered for modelo 036, you’ll need a lot of different information points and documents, 2 of which that can often cause confusion are your epígrafe and CNAE Code.
Your IAE epígrafe is a 3-4 digit tax code for hacienda, that is based on the type of work you do. Make sure your IAE is correct, because it determines your tax obligations and the invoicing rules that apply to you. If you're unsure which code fits your activity, check Hacienda's IAE classification or ask your gestor before you do your submission.
Your CNAE is the Social Security's equivalent activity code. It describes your activity for different administrative purposes, so make sure you use the appropriate code in each registration. For your CNAE activity code, you can use Hacienda’s Tax Registry and Economic Activities Tax virtual assistant tool to search for the activity relevant to you.
How to submit modelo 036
You can complete and submit modelo 036 online via the AEAT Sede Electrónica at agencia.tributaria.gob.es using your digital certificate or Cl@ve. The process takes around 20–30 minutes and you'll receive confirmation immediately.
Step 2: Register with Social Security (RETA) via Import@ss
Once you've registered with Hacienda, it's time to register with the RETA — the Régimen Especial de Trabajadores Autónomos (Self-Employed Workers' Social Security Regime). This is how you pay into the Spanish Social Security system as a self-employed person.
You can do this via Import@ss using your digital certificate or Cl@ve.**
How to access Import@ss:
Go to importass.seg-social.es and log in with your digital certificate or Cl@ve. Navigate to 'Afiliación' > 'Alta en RETA'.
What you'll need to complete:
Start date - this must be exactly the same as the one you used in Modelo 036. No wiggle room here.
IAE code- the one you identified in step 1
CNAE code - the one you identified in step 1
Mutua colaboradora - you need to choose a collaborative insurance body (mutua). This covers your professional contingencies and activity cessation benefit. Without it, you won't have any cover if you have an accident or need to go on sick leave.
Contribution bracket - in 2026, your monthly contribution is based on your estimated net income. You pick the bracket that best reflects what you expect to earn this year (more on this below). For more detail, see our guide: RETA registration online explained.
Your bank account’s IBAN - to make sure that money transfers -such as your monthly RETA direct debit - are routed correctly.
Once you’ve gone through the online process, download and save your confirmation document. You'll need it to open certain bank accounts, take on contracts, and prove your employment status to the government.
Key deadlines: when you need to register
You must register by the day you start trading. However, if you want to get a head start on things you can register up to 60 days before you start trading.
It’s worth knowing that the dates on your Hacienda registration (modelo 036) and RETA registration must match exactly. Hacienda and Social Security cross-check these dates. A mismatch is one of the most common mistakes, and one of the most easily avoided. With Monzo Business you can avoid this entirely by quickly and easily registering with Hacienda and Social Security at the same time.
The flat-rate contribution for new autónomos in 2026: what it is and how to claim it
What is the tarifa plana?
If you're registering as self-employed for the first time (or returning after a gap of at least 2 years), you're entitled to a reduced RETA contribution for the first year, which is known as the tarifa plana.
New autónomos pay a flat monthly contribution for their first year (regardless of income). This monthly contribution is €80, but you’ll also need to pay MEI, which makes it €88.64 a month, provided they choose the lowest contribution bracket.**
To see how your tarifa plana might affect your take home pay, you can use our autonomo calculator.
Who qualifies?
In order to get access to this reduced rate, you must not have registered as autónomo in the preceding 2 years (3 years if you previously benefited from the flat rate)
The reduction applies for 12 months. You can request this during RETA registration, you don't need to apply separately. If you’re not sure whether you qualify, then check with your gestor.
What happens when the 12 months are up?
Once your first year ends, your contribution is calculated based on your actual net income. If you earn less than the Salario Mínimo Interprofesional (SMI), you can get further reductions to your contributions, by extending the tarifa plana another 12 months.
This doesn’t happen automatically as you need to request this explicitly through Import@ss before your tarifa plana expires. If you don't apply in time, you miss it.***
You can see how your tarifa plana affects your take home pay with our calculator.
The most common mistakes when registering as autónomo (and how to avoid them)
Registering with Hacienda but not with the RETA (or vice versa) - both registrations are mandatory. One without the other means you're not operating legally.
Registering in the wrong order - register with Hacienda first, then with RETA. Doing it the other way round may delay your RETA registration or mean you need to fix it.
Registering after you’ve started working - this is where problems can get costly. You could lose discounts, pay contributions from an earlier date and face extra charges.
Using different start dates - the date on your Modelo 036 and your RETA registration must match exactly. A mismatch will cause issues when contributions are reconciled.
Choosing the wrong IAE epígrafe - this has direct tax consequences. If you're unsure, speak to an adviser before submitting the form.
Not saving your confirmation documents - always download your Hacienda registration confirmation and your Import@ss certificate. You'll need them to open bank accounts, take on contracts, and deal with the government.
Not choosing a mutua - it's mandatory, and without one you have no cover if you're injured or fall ill.
With Monzo Business, registering as autónomo is part of opening your account. Our partner Legálitas takes care of Hacienda and RETA in the right order, with matching start dates and the correct epígrafe, and keeps the confirmations you'll need later.
What to look for in a business account as an autónomo
When completing your Social Security registration as an autónomo, you’ll need a bank account to set up the direct debit for your monthly RETA contribution. Legally, you can use a personal account - but having a separate business account can make your financial life significantly easier.
With a dedicated business account, you can see at a glance what's coming in and going out of your self-employed activity, keep your professional income separate from your personal spending, and make your quarterly VAT and income tax returns much more straightforward.
What to look for in a business account as an autónomo:
Spanish IBAN (to simplify RETA direct debits)
A bank that is an Entidad Financiera Colaboradora (this is required for the RETA direct debits)
Bizum integration for easy payments to and from customers and suppliers
Debit card
App-based management, no office visits required
With Monzo, you can register your business and open your business account together. No offices. No paperwork. Spanish IBAN and Bizum from day one.
We know registering as an autonomo can be complicated, so you can use our interactive checklist to help you tick off the actions as you.
Sources
*Agencia Tributaria: modelo 036 registration for autónomos: agencia.tributaria.gob.es
**Seguridad Social: RETA registration, contribution brackets and flat-rate reduction (2026): seg-social.gob.es
***Social Security - Colectivos: Trabajo Autónomo (portal.seg-social.gob.es)